August 3, 2023 By Top Crop Manager
Alberta Grains has released its recommendations for how growers can help mitigate and manage Fusarium head blight (FHB) in the province.
Over the past five to 15 years, FHB has occurred with increasing frequency and impact in central and Western Canada. The trend brings FHB management more to the front and centre of agronomic decisions, especially at this time of year which is a good time to scout for FHB infection in wheat head.
FHB causes economic losses in three ways: 1) yield losses; 2) downgrading of grains; and 3) mycotoxin contaminations leading to a potential inability to market grain. The direct on-farm economic impacts of FHB, as estimated by a study in 2018, are shown in the following table. The grading factor is according to Canadian Grain Commission.
Management measures suggested by Alberta Fusarium Head Blight Management Plan
Currently, there are many measures to prevent the spread of FHB and manage FHB. As no single tactic will completely eliminate the risk of FHB, farmers are highly encouraged to implement a multi-pronged approach to reduce crop risk. The recommended tactics include:
Continuous or short rotation cereals or corn promotes the buildup of Fusarium spp. pathogens on crop residues. It is recommended to leave at least 2 years between host crops (small grain cereals and corn).
Genetic resistance to FHB is quantitative. Multiple genes are required to obtain a desired level of FHB resistance, similar to laying bricks to build a wall. This makes complete resistance much more difficult to achieve.
Seed test and use seed treatment to minimize the introduction of Fg onto farm and into fields through seeds. This is especially important for farms and fields with no history of downgrading due to Fg infected grain.
Seed testing is one of the more important tools to prevent introducing or spreading Fg on the farm. Farms should be checking their seed lots yearly to understand infection levels and, where possible, use that information to prevent the spread of infection to fields that have not shown history of Fg infection. Two seed testing methods are available. Each method has its pros and cons. Therefore, producers should pick the method most appropriate for the farmers situation and needs.
Along with crop rotation, variety selection and seed testing, the use of seed treatments provides additional reduction in FHB risk.
Use a fungicide seed treatment registered in Alberta for control of seedling blight and suppression of root and crown rot caused by seed and soil-borne Fusarium spp.
Scouting, monitoring and risk assessment
Surveillance and scouting plays a key role in understanding disease prevalence on farm and subsequent farm management decisions. Scouting, seed testing; monitoring of FHB risk map and assessing farm-specific variety choice, disease history etc. should be used together to understand on-farm risk. When on-farm risks are assessed, appropriate mitigation measures can be implemented to reduce infection risk.
The decision to spray an FHB fungicide includes many factors including, but not limited to, FHB infection history, weather conditions, risk tolerance, variety selection, cropping history, and farm logistics. When risk of FHB is present, growers should consider using a fungicide. Fungicide is most efficient at suppressing FHB when applied at early anthesis (another just appeared) with good spray coverage. It is important to understand that a fungicide application will not completely eliminate FHB infection.
Seeding and irrigation management
Seeding practices help establish a healthy, uniform crop, as well as mitigate risks.
– Increased seeding rates: promotes more uniform stand and shorter flowering period (the stage most at risk for infection) in the same field
– Target seeding rate for wheat and barley
– Stagger planting dates: staggered planting dates will subsequently stagger the flowering dates between fields. This practice helps avoid having all fields flowering and being exposed to FHB risks at the same time.
– Avoid excessive irrigation during the flowering period. Excess moisture at flowering creates a canopy microclimate conducive for increased FHB infection. Instead, look to top up soil moisture prior to heading/flowering to increase the amount of time required between irrigation events.
Field hygiene / biovigilance
Remove any loose crop residue from all equipment before leaving an infected field and moving to another field. To encourage more rapid decomposition of infected crop residue, chop the straw and evenly distribute.
In 2020, F. graminearum was deregulated from Alberta Agricultural Pests Act, leaving the options to municipalities to create bylaws.
Check with local municipality for F. graminearum bylaws.
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